Today's trend is to configure separate networks for management, virtual machines (VMs) and migration of VMs in virtual datacenters. Typically, in such virtual datacenters a set of virtualization-based distributed infrastructure services provides virtual machine monitoring and management to automate and simplify provisioning, optimize resource allocation, and provide operating system and application-independent high availability to applications at lower cost and without the complexity of solutions used with static, physical infrastructure and other such environments. One of these distributed services is, a failover service, which provides easy-to-manage, cost-effective (high availability) HA clusters for all applications running on VMs that are often used for critical databases, file sharing on a network, business applications, and customer services, such as electronic commerce websites. In the event of a server hardware failure, affected VMs are automatically restarted on other physical servers during a failover operation to reduce downtime and information technology (IT) service disruption and to further reduce any dedicated standby hardware and installation of additional software requirements.
However, if a host computing system is partially isolated (i.e., isolated from management and virtual machine networks and not the migration network) from the other host computing systems in a high availability (HA)) cluster in the virtual datacenter, any VMs running on the partially isolated host computing system may end up in two scenarios. In the first scenario, if the VMs running on the partially isolated host are kept powered on, then the VMs may not be accessible to any users as the VM network is isolated from the failed host computing system. In the second scenario, if the VMs running on the partially isolated host computing systems are powered off, the associated failover agent may power them in at least one other host computing system in the failover cluster and this can result in losing state of guest operating system (guest OS) and applications running on the VMs before the failover occurred.